STING agonist A4 is a potent, specific STING agonist, effectively activates STING in both human THP1 and mouse RAW 264.7 cells with EC50 values of 0.06 and 14.15 μM, respectively.
A4 demonstrates remarkable binding affinities to various hSTING variants and mSTING with IC50 values ranging from 0.77 to 2.64 μM
A4 more effectively stabilizes STING in its active conformation, compared to SR-717.
A4 binds to hSTING REF protein with substantially better affinity than SR-717 (Kd = 3.23 vs 526 nM) in ITC assays.
A4 effectively activated the STING signaling pathway, induces phosphorylation of STING downstream proteins as TBK1, IRF3, and p65 in THP1 cells,  displays remarkable capabilities in inducing the mRNA expression of target genes IFNB1 and IL6 in a concentration-dependent manner in RT-qPCR analysis.
A4 (5 and 10 mg/kg, i.v.) significantly elevated plasma IFN-β levels in C57BL/6 mice, significantly inhibited tumor growth, with tumor growth inhibition (TGI) rates of 51.23 and 74.45%, respectively B16.F10 xenograft mouse model.